A tempering and coating plant of the type described above is known from the journal "Zucker- und Susswaren-Wirtschaft" (Sugar and confectionery industry), Issue 4, 1990, pp. 135-138. The two subassemblies are mounted to the left and right of the conveyor belt and the two coating machines can be employed in alternation. In doing this, the subassembly for white chocolate is not cleaned. The subassembly for non-white chocolate is either employed only for one type of non-white chocolate or, however, for example, in the case of alternate use for plain and for milk chocolate, rinsing or cleaning of the affected parts of the subassembly must be carried out. This can take place while the subassembly for white chocolate is in operation. The known subassemblies are equipped with rapid-action couplings, with respect to the chocolate lines, the use of which enables the lines to be uncoupled or, in the moved-in (operational) state, coupled respectively. These rapid-action couplings must at least be provided in the connecting line between the tempering machine and the coating machine and in the return line between the coating machine and the associated tank of each subassembly. The mechanical changing of the coating machine and the restarting of the respective tempering machine requires at least approx. 45 min. As the parts concerned are decoupled by means of the rapid-action couplings, it is also not possible to have the tempering machine in stand-by mode while the coating machine is in its moved-in state. Incidentally, the coupling and uncoupling of the rapid-action couplings involves chocolate losses.
Furthermore, a tempering and coating machine is known in which only a single subassembly consisting of one tempering machine and one coating machine is employed. If a change takes place here, then differing consequences result according to the particular succession of the various substances. With a change between dark chocolate and milk chocolate this can be done by simply changing the mass with subsequent rinsing. Mixing of smaller residue does not play any role here. However, with a change between milk chocolate or dark chocolate and white chocolate, extensive cleaning of the subassembly, including the lines, is necessary. The is carried out by carefully washing the coating machine and the tempering machine, something that demands time and a break in production lasting several hours. In order that such a subassembly can be cleaned in such a washing procedure, all parts which come into contact with the chocolate must be manufactured from stainless steel. The necessary wet cleaning with hot water increases the risk of biological contamination, especially the danger from salmonella. As chocolate masses normally contain less than 1% moisture, there would seem to be no danger from salmonellae, i.e. from the point of view of the mass itself. It is only the wet cleaning or cleaning water residue respectively which increases the danger from salmonellae.